In recent years, with increasingly powerful functions, mobile devices have gradually replaced the music players, cameras, electronic game players and other electronic devices, for playing music, taking pictures and playing games. However, when using an earphone for listening music, a user may be affected by the external noises, such as passers-talk sound and traffic noise. Thus, there is a strong demand for noise-canceling earphone which is capable of reducing or even eliminating the external noises. However, the conventional noise-canceling earphone usually needs an additional battery to supply the operation power for the noise-canceling earphone; consequentially, the noise-canceling earphone may have relatively-large size and increasing weight. In addition, because the operation power is provided by batteries, the issue of poor noise canceling effect caused by insufficient operation power may occur. Thus, for a user, it is not such convenient to use the conventional noise-canceling earphone.